Sen. Patrick Leahy, the powerful chairman of the chamber’s Judiciary Committee, on Tuesday strongly endorsed a series of sweeping restrictions on U.S. surveillance programs — from ending the bulk collection of Americans’ phone call logs to creating new oversight mechanisms to keep the National Security Agency in check.

In a speech at Georgetown University Law Center, the Vermont Democrat said the government “has not made its case” that the ability to collect Americans’ phone records en masse under the PATRIOT Act is “an effective counterterrorism tool, especially in light of the intrusion on Americans’ privacy rights.”

As the senator criticized the program, authorized under Section 215, he also pledged to explore “possible structural changes” to the secret court that reviews government surveillance requests. And Leahy said he planned to work with his Republican colleagues in the House to rein in the Foreign Intelligence Surveillance Act, which governs the NSA’s ability to tap Internet communications as it scours for foreign terror suspects.

Leahy’s speech Tuesday marks his committee’s return to the thorny, complex surveillance debate, sparked by contractor Edward Snowden. Even as Snowden’s leaks continued to make headlines, lawmakers disengaged as they turned their attention to Syria and the debt ceiling.

The chairman’s panel plans to hold a classified briefing on the NSA on Wednesday, with an open hearing to come next week featuring testimony from Director of National Intelligence James Clapper and Gen. Keith Alexander, the dual leader of the NSA and U.S. Cyber Command.

Leahy’s committee isn’t alone in its inquiry: The Senate Intelligence Committee promised its own series of hearings on NSA data collection this fall. The Intelligence panel announced that its first hearing on FISA will occur Thursday — and it will also feature Clapper and Alexander, as well as Deputy Attorney General James Cole.

Leahy is set to play a critical role in shaping the reform debate. He previewed his approach in the Georgetown speech, saying Congress must “recalibrate” government surveillance while finding “a way we can discuss publicly the outer bounds” of the NSA programs.

The senator affirmed his interest in restricting Section 215 under the PATRIOT Act, specifically to prohibit “bulk collection of Americans’ phone records.” He introduced a bill this summer to that effect, and the measure currently has 10 co-sponsors, including Sens. Ron Wyden (D-Ore.), Mike Lee (R-Utah) and Richard Blumenthal (D-Conn.).

The measure still would allow the “intelligence community to continue collection under Section 215 and other authorities if appropriately tailored and targeted,” according to Leahy.

Leahy also called for a “hard look at the existing oversight structure and what we are asking of the judges appointed to the FISA court.” Those judges, he explained, have taken on a “regulatory role not envisioned in the original version” of the law. And the court, he said, hamstrung by the NSA’s misunderstanding of its own programs or the agency’s misleading statements, hasn’t always been able to conduct meaningful oversight.

Leahy rejected the idea that the FISA court is an “unthinking rubber stamp,” but he did raise the possibility that Congress will rethink the court’s responsibilities and structure. That would certainly satisfy some Democrats on his committee, who have unveiled legislation that would change the way FISA judges are appointed while naming a special public defender, of sorts, to argue for privacy interests against government surveillance requests. Leahy, though, is not currently a co-sponsor of that bill.